Such an exhaust line is provided to equip an internal combustion engine, for example a Diesel. It includes a system for reducing the nitrogen oxides and an injector for a reducing agent, such as urea, placed upstream of said system. The most widespread configuration of the urea injection zones is generally situated between a particle filter (preceded by an oxidation catalyst) upstream and a selective catalytic reduction (SCR) of the nitrogen oxides downstream. Another fairly widespread solution consists of placing the injection zone between the oxidation catalyst and either an impregnated particle filter to treat the nitrogen oxide reduction, or an SCR catalyst followed by a traditional particle filter.
However, in both cases, the current injection zones comprise, from the outlet face of the upstream block (which is either a particle filter or an oxidation catalyst) as far as the inlet face of the following block (which is either an SCR catalyst, or an SCR impregnated particle filter or an SCR catalyst followed by a standard particle filter): a convergent cone that reduces the gas passage diameter, a tube supporting the injector, and a divergent inlet cone that increases the gas passage diameter. Furthermore, in most cases, the injection zones comprise a mixer inside the tube after the support for the injector.
Such an arrangement imposes an incompressible link, in particular due to the presence of the convergent and divergent cones. Furthermore, to ensure correct operation of a urea injection system, it is necessary for the injection, evaporation, hydrolysis-thermolysis of the urea into ammonia, and mixing of the ammonia with the exhaust gas functions to be ensured so as to obtain a very homogenous dispersion of the ammonia in the exhaust gases on the intake face of the downstream block. This conversion of the urea into ammonia and the mixture between the ammonia and the exhaust gases require time, and therefore a significant path distance.
In all, by optimizing the different functions as much as possible, the distance between the two blocks can be reduced to 200 mm. Nevertheless, such an arrangement with a reduced distance is delicate and costly to produce.
In this context, the invention aims to propose an exhaust line having a more satisfactory operation, a reduced bulk, and a lower production cost.